Hi all, trouble shooting under way here. Can somebody please tell me how to undo the voltage regulator plug! It's driving me crazy. What am I supposed to be pressing on to release it?

Thanks!

10-19-2017, 09:48 PM

beano08

Never mind, whew. That was on there tight

10-19-2017, 11:34 PM

happy wanderer

I think every airhead owner who likes to wrench their own bikes should get one of this wonderful book on troubleshooting charging systems. Top of the page here: [URL="http://www.motoelekt.com/goodstuff.htm"]http://www.motoelekt.com/goodstuff.htm[/URL]

I also think Oak's top end manual should be near your toolbox too and used every time you need to pull the heads. It's very well written and easy enough to follow along and avoid common mistakes. Oak has sadly passed away but I believe his top end book is still available from his wife. Sorry I can't seem to find her contact info but searching here for "Oak top end" should yield results.

10-20-2017, 12:15 AM

beano08

Yes, I've heard great things about Rick's book. I definitely plan on adding to my toolbox. I've actually ordered some plug wires from him. He's a great guy.
So I jumped the voltage regulator and unfortunately the charging light did not go out. What would the next step be? Diode board? My understanding is that an open rotor results in no light. Is that true? The brushes looked OK to me, but I didn't do any scientific tests on them

10-20-2017, 12:36 AM

20774

[QUOTE=happy wanderer;1107438]I think every airhead owner who likes to wrench their own bikes should get one of this wonderful book on troubleshooting charging systems. Top of the page here: [URL="http://www.motoelekt.com/goodstuff.htm"]http://www.motoelekt.com/goodstuff.htm[/URL]

I also think Oak's top end manual should be near your toolbox too and used every time you need to pull the heads. It's very well written and easy enough to follow along and avoid common mistakes. Oak has sadly passed away but I believe his top end book is still available from his wife. Sorry I can't seem to find her contact info but searching here for "Oak top end" should yield results.[/QUOTE]

Certainly, Motorrad Elektrik's charging book is well worth the price of admission. Snowbum has an alternator troubleshooting page here:

[url]http://bmwmotorcycletech.info/trbleshootALT.htm[/url]

Not sure you've said what year/model you have, but here's another page that has additional electrical information:

[url]http://w6rec.com/bmw-motorcycle-5-electrical/[/url]

10-20-2017, 12:38 AM

20774

[QUOTE=beano08;1107443]So I jumped the voltage regulator and unfortunately the charging light did not go out. What would the next step be? Diode board? My understanding is that an open rotor results in no light. Is that true? The brushes looked OK to me, but I didn't do any scientific tests on them[/QUOTE]

I think the purpose of jumping the regulator was to find out if there was a voltage increase when doing so. If the regulator is at fault, I believe the voltage will increase dramatically when the engine is revved. If it didn't increase, then you definitely have an alternator problem. Time to methodically go through the above links.

10-20-2017, 02:37 AM

beano08

There was no increase in Volts at the battery terminals. So it's definitely a charging issue. Again, it was my understanding that an open rotor would show as NO charging light. Can anyone confirm this? Also, I don't believe I mentioned it; the bike is a 76 R75

10-20-2017, 03:14 AM

PGlaves

[QUOTE=beano08;1107460]There was no increase in Volts at the battery terminals. So it's definitely a charging issue. Again, it was my understanding that an open rotor would show as NO charging light. Can anyone confirm this? Also, I don't believe I mentioned it; the bike is a 76 R75[/QUOTE]

Indeed, an open rotor will not allow the light to light. The bulb is in series with the rotor so if the rotor is open there is no path to ground through the bulb.

10-20-2017, 01:47 PM

beano08

Ok, so that leaves what? A closer inspection of the brushes? The wires connecting the stator to the diode board or the diode board itself. I mentioned that I did have the board out. It looked OK, no melted soldering or cracks but I suppose they can still go bad. I'm not giving up yet, I'm just getting this sinking feeling that I have some strange issue that's going to be a nightmare to figure out.

10-20-2017, 02:30 PM

m_stock10506

[QUOTE=happy wanderer;1107438].............
I also think Oak's top end manual should be near your toolbox too and used every time you need to pull the heads. It's very well written and easy enough to follow along and avoid common mistakes. Oak has sadly passed away but I believe his top end book is still available from his wife. Sorry I can't seem to find her contact info but searching here for "Oak top end" should yield results.[/QUOTE]

I requested this info in a recent thread. I also noticed in the most recent issue of "Airmail" the ABC monthly, that Oak's column is continuing publication. This is because he provided many months of technical advice to the readers. In the Airtech column, they provide the info to order Oak's Top End Manual. Order goes to his wife, Carol Okleshen. $30.
22637 Ridgeway Ave
Richton Park, IL 60471

I ordered a copy a week ago. Nothing yet.

10-20-2017, 07:58 PM

happy wanderer

[QUOTE=beano08;1107480]Ok, so that leaves what? A closer inspection of the brushes? The wires connecting the stator to the diode board or the diode board itself. I mentioned that I did have the board out. It looked OK, no melted soldering or cracks but I suppose they can still go bad. I'm not giving up yet, I'm just getting this sinking feeling that I have some strange issue that's going to be a nightmare to figure out.[/QUOTE]

Well, as Paul just stated if the rotor is open the charge light will go out. If it's flaky you will see dim, intermittent and other odd behaviour of the light. The easiest way I know to test it is to simple lift up the brushes and slip a match book cover or other small thin piece of cardboard or plastic under the brushes so they are no longer contacting the slip rings on the rotor.

Then take your meter set on OHMS and measure the resistance of the rotor by touching the leads to the two slip rings. If you get NOTHING or OPEN then the rotor is no good, Get a new one from EuroMotoElectrik or Rick at Motorrad Electrik. You will need the special bolt to get it off.

Inspect the brushes closely while you are in there. Next to the rotor which is probably the number one failure to charge culprit the brushes being worn out and not making proper contact becasue they are simply too short to reach the slip rings anymore is probably number two.

I would still not rule out some corroded wiring hiding somewhere. The connector on the BACK of the diode board (the one you cannot see till you remove the diode board) is also a well hidden culprit in charging issues. I think Greg Hutchison mentioned this recently as well...

Use Kurt's links and be methodical starting at the rotor and keep a running list of what you've looked at. You'll find the problem. I'm still not ruling out the regulator...

10-20-2017, 08:24 PM

20774

With the brushes lifted and matchbook cover isolating them, if you put a penny across the slip rings (only touch the two slip rings) and see if the gen lamp lights up, the rotor is bad. Snowbum has a thorough discussion of all tests.

10-20-2017, 09:26 PM

happy wanderer

[QUOTE=20774;1107504]With the brushes lifted and matchbook cover isolating them, if you put a penny across the slip rings (only touch the two slip rings) and see if the gen lamp lights up, the rotor is bad. Snowbum has a thorough discussion of all tests.[/QUOTE]

Yeah that works but I like to isolate one thing at a time. The penny test relies on the wiring and bulb connections to be good in order for the light to work. The ohm meter simply tests continuity of the winding. And we know from lots of failures that when there is no continuity the rotor has an issue of either a dead short from melted insulation or it is open due to wire breakage somewhere in the winding.

The owner does seem to have a working bulb in this case so the penny test should work.

10-20-2017, 09:30 PM

20774

MJM -

You're correct. The whole idea is a thoughtful process of working through the system until the problem is revealed. That's what's so good about Motorrad Elektrik's book...that's the way it is designed.

10-21-2017, 01:33 AM

beano08

I'm blown away by you folks taking time to help a fella out. Ok i've got the bike apart right now and I think I may have found the issue! My rotor is showing open. There's no ohms coming up on my multimeter. But going back to an earlier question, how is it that I'm still getting a gen light? Is there any conceivable way that these bikes can have a bad rotor and a gen light on?